Hi,
Is the file being generated in a project that is referenced by the project containing the code that is using it?
If so, you need to be aware of how NCrunch wires together application domains across its workspaces. See
http://www.ncrunch.net/documentation/considerations-and-constraints_assembly-colocation-assumptions.
Under NCrunch, the AppDomain.CurrentDomain.BaseDirectory will be set to the output directory of the test assembly. If you're looking for the output directory of one of your production assemblies, the safer way to locate this is by instead using reflection to find it. For example: typeof(TypeWithinAssembly).Assembly.Location
Turning on the 'Copy referenced assemblies to workspace' setting for the projects involved will often solve these problems, but this comes with a significant performance cost.